In some disk drives, a member (ramp member) having a ramp (slope) is provided in the proximity of the outer periphery of the disk to be used to retreat a head. To control the position of the head over the disk appropriately and within a wider range, a contact point at which a member proximal to the head contacts with the ramp member on the disk is desired to be detected. By detecting the contact point, preferable recording surface can be provided on the disk.